Original question: ‘How to treat Head lice and in particular how effective is Neem oil?’
A very relevant question, reoccurring every summer with the advent of the head lice ‘season’.
Neem oil is an ingredient in many naturally derived pesticides so I suspect that it could be reasonably effective.
However exactly how effective against a nasty little pest that is fast becoming extremely resistant to many other remedies I do not know.
Neem oil is made from the seeds of the Neem tree (azadirachta indica) a native of India. The oil has been traditionally used as an anti-fungal, anti-bacterial, anti-viral, for skin
diseases and as an insect repellent.
The Internet contains many references to it being effective against lice with quite a number of ideas on how to get best results.
Some references are to mixing it ½ ounce of Neem oil to 8 ounces shampoo or to 10% Neem oil to 90% coconut oil.
Traditional use in India apparently was to use neat Neem oil applied directly to the
scalp. It would depend on how sensitive the scalp is.
All recommend leaving in the hair over night for best result although some
retailers of ‘lice’ shampoos maintain that the addition of other essential oils such as eucalyptus, rosemary, lavender, tea tree and citrus extracts speed up the killing process and long exposure is not necessary.
I’m not sure of the method by which it kills the lice, as some references say by starvation of the insect, others say by affecting the nervous system. However because of the resistance of lice to many known ‘remedies’ I would tend to think that leaving the oils on for the longer time would be likely to be the surest method.
Also many of these oils may kill the live insect quite efficiently but not the eggs, so a repeat application is always an advisable idea and where re-infestation is likely better still to use the oils at every shampoo.
Studies done on the use of ‘orthodox’ head lice treatments have shown that in many cases
the treatments were not being used in sufficient quantity when shampooing, up to 20ml per shampoo for short hair was recommended and up to 50ml for longer hair.
This is important in order not to promote further resistance to treatments.
I have also seen a study that indicated that one reason for the increase in head lice around the world could be due to the decline in the habit of hair brushing. Apparently vigorous brushing damages the lice, it dies, and helps break the reproduction cycle.
The maximum life of a louse is about 40 days. The females lay 7-10 eggs daily, touching or nearly touching the scalp, as this is the only place with the right temperature for hatching.
The louse feed up to 5 times daily and while feeding injects saliva containing anticoagulant which causes the hosts sensitivity and itchy head.
So out with the hair brushes and 100 strokes each morning like great grandmother did!